Process and apparatus for treating petroleum oils



Jan. 21, 1930. w, M. CROSS 1,744,262

PROCESS AND APPARATUS FOR TREATING PETROLEUM OILS Original Filed Dec;- 17, 1925 INVENTOR. M 2% flZ'leJs: BY A ATTORNEY.

. Patented Jan. 21, 1930 WALTER M. CROSS, 0F INSAS CITY, MISSGURI PROQESS AND APPARATUS FOR TREATING PETROLEUM OILS Application filed December 17, 1925, Serial No. 76,029. Renewed August 9, 1929,

This invention relates to improvements in a process and apparatus for treating oils, and

refers more particularly to a process for cleaning, dehydrating and relieving petro- 6 leum oils of their light oil content, including such fractions as naphtha, gasoline and gasoline-like cuts.

The process is primarily a distillation process preferably operated only at relatively low pressures.

The single figure is a diagrammatic side elevational view of the apparatus.

' Referring to the drawings, at 1 is shown a storage tank; 2 is a charging pump; 3 and 4 are coils positioned inthe top of the towers .5 and 6, respectively. Seven (7) is a separator; 8 is the secondary heating furnace, and 9 are the second heating coils positioned in the furnace 8. At 11 is shown a vaporizer having a vapor line connection 12 with the tower 6 and a draw off line connection 13 with the cooling coil 14 in the cooling box 15. The tower 6 is connected with the tower 5 by vapor line connection 16 in which is in-' terposed a partial cooling means 17. At 18 is shown a partial cooler or reboiler in which is positioned a coil 19 and a perforated pipe 20 connected to the discharge line 21 of the bubble tower' or dephlegmator 5. A vapor line connection 22 passing off from the top of the tower 5 leads to a final condenser 23 in the discharge 24 of which is positioned a look box 25. In the drawoif line 26 from the reboiler 18 is a cooler 27 and a look box 28 and in the draw off line 29 from the tower 6 is a cooler 30 and a look box 31.

Referring now to the method of operation, the oil, preferably a crude oil, is charged from the storage tank 1, passing through the line 32 to the pump 2 where it is directed through the line 33 through the coil 3 and line 34, coil 4, pipe 35, dividing into two lines 36 and 37 which terminate at the separator 7. By-pass lines 38 and 39 around the towers 5 and 6, respectively, controlled by suitable valves, furnish a means for by-passing the towers either wholly or in part so that the temperature of the Vapors passing off from the top of the towers can be accurate- 1y controlled. The manipulation of the valves for the by-passing of the towers 5 and '6 is automatically regulated by'temperature 1 level regulating device 40 which controls valves 41. When these valves are closed and the charging pump continues to introduce oil, a pressure is built up on the charging line and the preliminary heaters 3 and 4, this pressure being relieved by an automatic by-pass 42 which circulates a portion of the stock withdrawn from the tank 1 back to the tank without charging it to the system. The details of this local circulation or bypassing of a portion of the charging stock forms no part of the present invention.

The oil, in its passage through the preheater or preliminary heating coils 3 and 4, acquires sufficient heat to raise the oil above the boiling point of water at which temperature some of the lighter fractions of the oil are separated out in the vapor phase. Also, this preliminary heating dries the oils by driving off the moisture in the form of water vapor so that on its introduction to the separator 7 the water and lighter fractions pass off through the line 43 in the form of vapor and are directed to the fractionating tower 5. In place of the two preliminary heating coils 3 and 4 inthe top of the towers, a separate pipe coil positioned in the furnace may be used aswell and the preliminary heating accomplished in that way.

The liquid products from the separator are drawn ofi through the line 44 and are charged by means of a. pump 45 through the line 46 to the secondary'heating coils 9 positioned in the furnace 8. The separation of the vapors from the liquid in the separator 7 facilitates considerably the operation of the pump 45 which has to handle only liquid products instead of a combination of liquid and vapor products which is normally the practice where preheating equipment is used. In the coils 9 additional heat is imparted to i is to relieve the highly heated oil of a portion of its excessive heat by imparting this heat to the condensates discharged from the tower 5 in order to partially revaporize these condensates to extract additional light fractions therefrom. Furthermore, the extraction of this excessive heat from the heated oil passing to the vaporizer improves considerably the ultimate distillate recovered from the vapor and the residual product, that is, a more free flowing fuel oil better adapted to commercial purposes and consequently more marketable than would be the case were the oil to be passed direct and the entire heat imparted to the oil in the heating stage used to vaporize it. If a portion of this excessve heat is not extracted, the oil may be reduced to an asphaltic bottom or sludgy, coky mass difficult to withdraw and handle in storage and not easily marketable.

The drawotf from the vaporizer is effected through the line 13 by means of an automatic liquid level regulator 52 controlling the valve v53. The vapors passing to the initial fractionating or dephlegmating column through the line 12 are sub ected to a refluxing action in the tower by rising upwardly by a series of pans or bafile obstructions diagrammatically shown at 54. The condensate separated out passes down through the line 29 controlled by a valve 55, thence through the condenser 30 and look box 31 to suitable storage not shown. The overhead material from the tower 6 passes throug the line 16 and cooler 17. The vapors uncondensed in the cooler 17 pass into the reboiler and thence through the line 56 to the tower 5, while the liquid material is reheated in the reboiler by the coil 19.

By controlling the amount of cooling by regulation of the amount and temperature of water circulation in the condenser or partial cooler 17, the extent of condensation in this cooler or partial condenser may be regulated. Consequently, the amount of separated liquid will be increased according to the increased amount of condensation. This additional condensate will serve to augment the cooling of the highly heated oil passin through the coil 19 in the reboiler 18. Thus, regulation of condensation in the cooler 1;, a more or less control may be had upon the amount of cooling which takes' place in the reboiler. As an exam le, in actual practice when the oil passing t rough the reboiler through the coil 19 is insufliciently cooled, additional condensation is effected in the partial cooler 17, thus supplying additional cooling medium to the reboiler.

The tower 5 is preferably of bubble tower construction such as diagrammatically shown'in the broken-away portion at 57. The vapors in this tower are further dephlegmated, passing off from the top of the tower through the line 22 to the condenser 23 and thence to gasoline storage through the line 24. The condensate separated out in the tower 5 is directed back to the reboiler through the line 21 and the perforated horizontal pipe 20. The liquid level in the reboiler is controlled by a liquid level regulating mechanism 58 controlling a valve 59 in the drawofi line 26. This withdrawn liquid from the reboiler passes through the line 26 to suitable storage.

The valve 60 is interposed in the draw off line 24 and by means of this valve any desired pressure may be imposed upon the system.

If the process is used for the dehydration of oils, the fractionating equipment will be considerably curtailed and to a great extent eliminated, the vapors being utilized solely as a preheating medium for the oil passing to the separating stage. The cleaned oil .would be taken 01f from the separate tower stages with a relatively small percent passing overhead to the final condenser.

The advantages of the system lie primarily in that crude oil or residuum containing water or foreign substances, such as salt, sand, clay or dirt of any kind, are separated from the impurities in the preliminary heating and separating stages. Furthermore, these light oil vapors and steam vaporized in the preliminary heating and separating stagesdo not proceed with the liquid oil'to the secondary heating stage where their presence would detract from an elfective handling of the liquid products and effective heating of the liquid material. Also, their absence permits of a better heat exchange as considerable heat can be taken up unnecessarily by such vaporous material. In addition to this, the liquid oil heated in the heating stage is raised to such a temperature at which it may be partially cooled and subsequently vaporized to produce the light oil fractions in the form of vapor and a marketable fuel oil residual bottom.

The treating or heating of the oil in the system is such that the material drawn off from the separator and charged to the secondary still is out of equilibrium, that is, the oil does not containacomplete range of cuts or fractions corresponding to ,the original crude as the lighter fractions of the oil have been removed by the preliminary heating and llia' separation. In the secondary heating stage, in addition to the distillation which takes place, there may be a limited amount of conversion, that is, there may be conversion to the extent that the equilibrium of the oil is restored by a conversion which would again supply to the oil those lighter fractions, either wholly or in part, which were eliminated in the preliminary heating and separating stages. This conversion or cracking will be inconsequential or considerable according to the heating in the secondary stage.

As an example of the relative yields upon the equipment described and upon the usual type of pipe still, an Illinois crude oil of approximately 32.5 Baum, treated by the common type pipe still operation, produced twenty-five (25%) per cent of gasoline having an end point temperature of 437 F. The oil under treatment in the pipe still was heated to a temperature of from 700 F. to 760 F. and from the bottom was recovered a residual of 12 to 14 Baum fuel oil. By the improved method explained, the same Illinois crude oil yielded, during actual commercial operation, thirty-five (35%) per cent of gasoline having an end point of 437 15. and an equally good fuel oil bottom of 12 to 14 Baum.

The economies in the process lie primarily in theutilizing of the heat of the oil vapors to accomplish the preliminary heating of the incoming charging stock or crude oil, the dephlegmation or refluxing of the vapors is to a certain extent effected by the heat exchange which takes place in this preliminary heating. Also, the partial cooling of the oil to be vaporized after the secondary heatmg is produced by a heat exchange with the reflux condensate which is knocked back from the vapor phase oil fractions, this heat serving to revaporize, to a considerable extent, these condensates.

ll claim as my invention:

1. A process for cleaning and topping crude petroleum, comprising the steps of preliminarily heating the oil to a temperature above the boiling point of Water by bringing it in radiating contact with hot oil vapors 1n fractionating stages of the system, separatmg liquid and vapor phase material from the preliminarily heated oil; directing the vapor phase productsto a fractlonating stage and the liquid phase products to a secondary heating stage where additional heat 1s lmparted thereto, passing the heated oil thence to a stage in which there is effected simultaneously a partial cooling of the heated 011 and a re-boiling of the reflux condensate separated in the fractionating stages, directing the heated oil thence to a vaporizing stage where it is introduced at a pre-determined temperature controlled to separate the vapor phase hydrocarbon fractions from a free-flowing densing the mixed vapors and withdrawing the residual products from the vaporizin stage.

2. A process for cleaning and topping crude petroleum, comprising the steps of preliminarily heating the oil to a temperature above the boiling point of water by bringing it in radiating contact with hot oil Vapors in fractionating stages of the system, separating liquid and vapor phase material from the preliminarily heated oil, directing the vapor phase products to a fractionating stage'and the liquid phase products to a secondary heating stage where additional heat is imparted thereto, passing the heated oil thence to a combined partial cooling and reboiling stage and thence to a vaporizing stage where it is introduced at a predetermined temperature, controlled to separate additional fractions of vapor phase hydrocarbons and a free flowing residual bottom, fractionating and condensing the vapor phase material from the vaporizing stage and Withdrawing the residual products from the vaporizing stage, reboilin in the reboiler and partial cooling stage t e condensate separated from thereof.

3. A process for cleaning and extracting the lighter fractions from crude petroleum, comprising the steps of preliminarily heating the oil to a temperature above the boiling point of water, separating the liquid and vapor phase material, passing the vapor phase products to a fractionating stage and the liquid phase products to a secondary heating stage where additional heat is imparted thereto, passing the secondarily heated oil to a combined reboiler and partial cooler and thence to a vaporizing stage and controlling the temperature at which the oil is introduced to the vaporizing stage to separate additional fractions of vapor phase hydrocarbons and a free flowing residual bottom from the oil while utilizing the excess heat in the oil prior to evaporation for reboiling in the reboiler and partial cooler a condensate separated out during fractionation, subjecting the Vapors evolved in the vaporizing stage to fractionation and final condensation.

4. In an apparatus for cleaning and topping crude petroleum, the combination with a primary and secondary heating means, of a separating stage interposed therebetween, a vaporizer connected to the discharge from the secondary heating stage, fractionating means and condensing means serially connected by a vapor connection to the vaporizer, a vapor connection between the separator and the fractionating means, a partial cooler adapted to reboil the reflux liquid interposed in t e discharge line between the secondary heating means and the vaporizer, 1i uid and vapor line connections between the ractionv ating means and the partial cooler, draw off lines from the vaporizer, fractionating means and final condenser.

- WALTER M. CROSS. 

